Archery bow sight



SeP- l, 1970 c. D. CROSBY 3,526,037

ARCHERY BOW S IGHT Filed July l2, 1968 2 Sheets-$heet l ASept. 1, 1970 c. D. CROSBY 3,526,037

ARCHERY BOW SIGHT Filed July 12, 1968 2 Sheets-Sheet 2 3,526,037 ARCHERY BOW SIGHT Charles D. Crosby, Rte. 4, Box 146A, Florence, Ala. 35630 Filed .Iuly 12, 1968, Ser. No. 744,565 Int. Cl. F41g 1/46, 1/00 U.S. Cl. 33-46 7 Claims ABSTRACT OF THE DISCLOSURE A bow sight in which a magnifying lens is pivotally supported in a carriage slidably mounted on a straight sight bar for elevational adjustments, in which a cam surface extending along the sight bar is engaged by a cam follower connected to the lens and causes the lens to be rotated as the carriage is moved along the sight bar so that the center of rotation of the optical axis of the lens will remain in an archers aiming eye when in some predetermined fixed position, and in which the cam follower is adjustably mounted with respect to the pivotal axis of the lens whereby the rate of rotation of the lens as it moves linearly may be varied.

This invention relates to sighting devices for archery bows of the type employing a sighting element or spaced sighting elements, the axes or sight lines of which are required to be rotated about a fixed center in the archers aiming eye as the sight is moved vertically on the bow in making elevational adjustments so that the archers aiming eye may remain in some predetermined fixed relationship with the nock end of the arrow when at full draw.

More particularly, the invention concerns the provision of novel means for rotating a sighting element at a substantially constant rate as it is moved vertically in making elevational sight settings and in providing means whereby the rate of rotation of the sighting element may be conveniently varied thereby to vary the distance from the sighting element to the center of rotation of its axis or sight line to accommodate variations as between archers in the distance from their aiming eye to the sight element when at full draw.

The U.S. Pat. #2,642,661 to Fredrickson, issued June 23, 1953, discloses an arcuate slot 22 in the bow handle in which sight element 26 slides, thereby causing the sight line to be rotated about a fixed axis as the sight is moved in making elevational adjustments.

The U.S. Pat. #3,267,577 to Markham, issued Aug. 23, 1966, discloses an arcuate slide bar mounted on a bow on which a slide block carrying a reflective sighting element slides and is hereby rotated as elevational adjustments are made so as to remain perpendicular to some fixed position to the archers aiming eye. It is also stated in the Markham patent, column 6, lines 1 to 8: For example, a straight slide bar with a cam surface lying alongside thereof for cooperation with a cam follower on support shaft 16 to cause rotational adjustment of the shaft and therefore angular adjustment of the reflecting surface as the slide block is moved up and down may be employed instead of a curved slide bar.

It is essential that the radius of curvature of the arcuate slot 22 of Fredrickson and the radius of curvature of the arcuate slide bar 10 in Markham be equal to the distance from the slot or slide bar to the archers aiming eye when in some preferred full draw position or it will be necessary for the archer to change his aiming eye position relative to the arrow nock in order to align the spaced sighting elements of Fredrickson with the target or in order that the aiming eye will be reflected in the mirror in Markham when the sight mount or slide block is moved vertically in changing elevational settings. For the same 3,526,037 Patented Sept. 1, 1970 ice reason, it is essential that the rate of rotation of the sight element, as by cam means, be precisely that which will maintain the center of rotation of its axis in the archers aiming eye as he sight element is moved in making elevational sight settings.

When using a single sighting element mounted on the bow, whether it is a pin, an aperture, or a magnifying lens with a dot or cross hair on the surface thereof, it is essential to maintaining the relationships of the sight line and the arrow axis, as predetermined by established elevational sight settings, that the archers aiming eye have the same fixed relationship with the nock end of the arrow at vfull draw. Under these conditions the aiming eye functions as a rear sight and any change in the position thereof relative to the nock end of the arrow will change the point of impact.

When the single sighting element is a magnifying lens with a sighting mark on the surface thereof, or very closely adjacent to the surface thereof, it is not only necessary to maintain a fixed relationship of aiming eye and arrow nock in order to maintain arrow axis and sight line relationships as predetermined by elevational sight settings, it is also essential to rotate the lens in a manner to maintain its optical axis substantially in the archers aiming eye as the lens is moved for elevational sight settings. This is necessary because a magnifying lens has curved surfaces and, therefore, any appreciable off axis sighting of the target through the lens will result in refraction, causing the target image to be displaced. It will be apparent that if the lens is moved vertically without suitable rotation thereof the degree of off axis sighting through the lens from a fixed eye position will vary as the lens is moved vertically, thereby variably displacing the image.

Inasmuch as the distance from the sighting element to the center of rotation of its axis varies with its rate of rotation as it is moved linearly, it will be apparent that some convenient means is needed to vary the rate of rotation to accommodate variations in the distance from the sight element to a fixed aiming eye position as between archers. In general this distance will vary directly with the archers draw length.

An abject of the present invention is to provide a generally new and improved bow sighting device in which a sighting element mounted for vertical adjustment on a bow is caused to rotate about a horizontal axis as it is moved vertically.

A further object is to provide a bow sighting device having a sighting element mounted for linear vertical movement on a sight bar and for rotation about a horizontal axis including means for rotating the sighting element as it is moved vertically, which means is adjustable to vary the rate of rotation of the sight element as it is moved vertically.

More specifically, it is an object to provide a bow sight in which a magnifying lens having associated sighting means is mounted for vertical linear movement on a bow and for rotation about a horizontal axis, in which a cam surface extending vertically along the bow cooperates with a cam follower connected to the lens and causes the lens to rotate as it is moved vertically, and in which the cam follower is adjustably mounted with respect to the horizontal axis of rotation of the lens whereby the rate of rotation of the lens may be varied.

Further objects and advantages will appear from the following description when read in connection with the accompanying drawings.

In the drawings:

FIG. 1 illustrates a sighting device constructed in accordance with the present invention, mounted on a bow held at full draw by an archer;

FIG. 2 is a side elevational view of a sighting device constructed in accordance with the present invention;

ZFIG. 3 is a front elevational view of the sighting device shown in FIG. 2;

FIG. 4 is an enlarged partial front elevational view of the carriage assembly;

FIG. 5 is a cross sectional view of the carriage assembly shown in FIG. 4, taken along line 5-5 of FIG. 4;

FIG. 6 is a side elevational view of the carriage assembly shown in FIG. 4;

FIG. 7 is a cross sectional view of the carriage assembly shown in FIG. 4 taken along line 7--7 of FIG. 4;

FIG. 8 is an enlarged cross sectional view of the carriage assembly and lens mount taken along line 8-8 of FIG. 2;

FIG. 9 is an enlarged side elevational view of the lens mount;

FIG. 10 is a side elevational view of the lens mount taken along line 10'-10' of FIG. 8;

FIG. 11 is a cross sectional view of the lens and mount taken along line 11-11 of FIG. 9;

FIGS. 12, 13, and 14 are side elevational, top plan, and end elevational views, respectively, of the carriage shown alone;

FIGS. 15 and 16 are side elevational and top plan views, respectively, of the pivoted member; and

FIGS. 17 and 18 are side and end elevational views, respectively, of the cam follower.

Referring to the drawings, the sighting device, generally indicated at 10, includes a vertically arranged, straight sight bar 12 shown connected to the string side of a bow 14 in FIG. l. The sighting device further includes a carriage 16 slidably mounted on the straight sight bar 12, a member 118 pivotally mounted in carriage 16 on a pivot pin 20, a leans or sight mount 22 supported on spaced pins 24 slidably mounted in pivoted member 1-8, and a cam follower 26 adjustably mounted on pivoted member 18.

The carriage 16, see FIGS. 12 to 14, has parallel side Walls 15 in which grooves 17 are formed. The grooves 17 receive the ribs or guides 19 extending along the sides of sight bar 12 in sliding tit relationship, see FIG. 7. The carriage 16 further includes end Walls 11 and 13 which do not extend to the sight bar. The spaced pins 24, slidably mounted in pivoted member 18, support a horizontal mounting stud 28 at their left-hand ends, see FIG. 8, and at their right-hand ends are connected by a plate 30. The mounting stud 218 has a head 27 and the pins 24 are connected at their ends to the mounting stud head 27 and to the plate 30 in any suitable manner, as by threaded engagement or by shouldering and riveting. In the preferred arrangement, I have shouldered and riveted the right-hand ends to plate 30 and threadedly engaged the left-hand ends in the head 27 of stud 28 so that they may be disassembled.

The plate 30` has a central perforation 29 which receives a reduced diameter portion 31 of a windage adjustment l screw 32 which is threadedly engaged in pivoted member 18 and positioned between pins 24. The right-hand end of screw 32 is milled to provide parallel flat sides 33 and is received in an accommodating axial perforation in a pressed-on thumb screw 34. As the thumb screw 34 is rotated the screw 32, being threadedly engaged in pivoted member 18, causes the plate 30 and, consequently, the pins 24 and sight mounting stud 28 to be moved to the right or left. The sight mount 22 .has a bore 23- which slidably receives the mounting stud 28. The left-hand end of mounting stud 28 has an internally threaded bore which receives a screw 25. When screw is loosened the sight mount 22 may be rotated. on stud 28, and when screw 25 is tightened, the sight mount is held in adjusted position. Clearance perforations 13a are provided in both of the carriage walls 15 to permit the pins 24 and windage adjustment screw 32 to pass through and to permit their rotation with pivoted member 18.

The sight mount 22 is further provided with a mounting ring portion 36 which receives a lens barrel 38 pivotally mounted therein on diametrically opposed vertical pivot pins 3-7, see FIGS. 8 to 11. The barrel 3.8l is somewhat smaller in diameter than the inside diameter of ring portion 36 so that it may be rotated to some degree therein on the pivot pins 37. Spaced axially from the pivot pins 37, see FIG. 11, are a pair of diametrically opposed horizontal set screws 40- threadedly engaged in the walls of mounting ring portions 36. The set screws 4() have hemispherical ends which engage the lens barrel 38 to hold it fixed in some desired adjusted position to which it is rotated on pivot pins 37. A converging lens 42 is suitably mounted in the barrel 38. The lens 42 may be of any suitable type, single or compound', and which to some degree magnies the target. The lens 42 has a sighting dot 43 at its center. llt is to be understood that any suitable sighting mark or marks, such as cross hairs, post reticule, or the like, may be substituted and that the sighting mark or element may be attached to the surface of the lens or mounted in the barrel 38 in axial spaced relationship with the lens. It is also to be understood that a system of axially spaced lenses mounted in the barrel may be employed.

The upper or string side surface of the sight bar 12 diverges downwardly with respect to the parallel rib portions or guides 19 and with respect to the bottom surface ofthe sight bar, thereby forming a cam surface 44 which is engaged by the cam follower 26 adjustably mounted in the pivoted member 18, see FIG. 5. This arrangement causes pivoted member 18 and therefore the sight mount 22 and lens 42 to be rotated counterclockwise, with reference to FIGS. 2 and 5, as the carriage 16 is moved dowuward on sight bar 12. The cam surface 44 is an inclined plane with respect to the plane of ribs 19 which enter the grooves of the carriage.

The cam follower 26 has an arcuate surface 21 which engages cam surface 44 and an opposed hat surface 46 which engages and moves slidably on a flat surface 48 forming the bottom of a recess 50 in the pivoted member 18. An adjusting screw 52 threadedly engaged in a threaded bore 53 in the pivoted member 18 at one side of the recess 50 has a non-threaded, reduced diameter portion 51 extending through a bore 57 in the cam follower 26 and projecting therefrom. The projecting end of reduced diameter portion 51 has a sleeve 54 press fitted thereon, and the sleeve 54 is journalled in a hole 55 in the pivoted member 18 at the other side of recess 50.

The shoulder formed by the reduction in diameter of the adjusting screw 52 bears against one side of cam follower 26, and the inner end of pressed-on sleeve 54 bears against its opposite side so that when adjusting screw 52 is turned the cam follower 26 is caused to move parallel with the adjusting screw and with the bottom 48 of recess 50. As wm follower 26 is moved by adjusting screw 52, the distance from the center of rotation of pivoted member 18 at pivot 20 to the point of contact of curved surface 21 with cam surface 44 will be varied, and, consequently, the rate of angular movement or rotation of pivoted member 18 as it is moved along the sight bar in carriage 16 will be varied.

In FIG. 5 the pivoted member 18 is shown in the intermediate angular position it assumes when at a mid-position of the inclined plane cam surface 44, and the cam follower 26 is shown in the intermediate position of its adjustment range.

When these conditions exist, the contact point of cam follower 26 with cam surface 44 and the axis of rotation 20 of the pivoted member 18 are intersected by a dotdash line 58 lying at approximately a 45 angle to the sight bar 12. Also, when the pivoted member 18 is in this position, the center of curvature of the arcuate cam follower surface 21 lies on a line perpendicular to the sight bar and passing through point of contact 56'.

From this mid-position the rotation of pivoted member 18 and therefore lens 42 in either direction will maintain a substantially constant relationship with linear movement of the carriage throughout the range of lineal movement in each direction ordinarily required for elevational sight adjustments. Also, the greatest range of adjustment of the cam follower 26 and therefore the greatest" change in rate of rotation of the pivoted member and leiis, without appreciable deviation from a constant relationship of rotational and linear movement, may be achievd when the cam follower 26 is adjusted both ways from the intermediate position shown. j;

In practice the rate of rise of the cam surface 44 may be made such that the rate of rotation of the leils when the cam follower is in its intermediate adjusted position will be the mean in a range of rotation rates considered necessary to accommodate most archers and mos't conditions of mounting of the sight bar on the bow.l ls

The pivoted member 18 is biased in a clockwise direction with reference to FIG. 5 by a relatively strong spring 60 which firmly urges the member 18 in position; against cam surface 44. The carriage 16 is locked in adjusted position on sight bar 12 by a set screw 62 which is threadedly engaged in a wall 15 of the carriage and bears against the slide bar 12, see FIG. 7. The rear llside of sight bar 12 is made somewhat narrower than the front or string side for the greater part of its length, as shown at 64 in FIG. 7 and in dotted lines in FIG. 3. Near the ends of the sight bar the rear side is made wider or equal to the width of the front side. This arrangement permits loosening of set Screw 62 sufficiently to allow carriage 16 to freely slide along the bar when making elevational settings, but prevents it from sliding off of the bar. In order to remove the carriage assembly from the sight bar, the screw 62 must be backed off to a considerably greater extent.

The front side or string side of sight bar 12 has a recess 65 for the insertion of a strip of tape on which elevational sight settings are indicated. An adjustable pointer 66 is provided. The pointer 66 comprises a wire element having a transverse portion extending over the recess 64 and a longitudinal portion lying in a groove 68 in one side of carriage 16. The diameter of the wire of which the pointer is constructed is slightly greater than the depth of groove 68, and a screw 70 threadedly engaged in carriage 16 has a head 71 which clamps the pointer 66 in adjusted position. y

In use the sight bar 12 is mounted on the bow so as to be perpendicular to the axis of the archers eye when his head is in the preferred position it will consistently assume when at full draw. Also, the sight bar 12 is preferably positioned along the bow so that when carriage 16 is positioned so as to place the cam follower contact point at mid-point of the inclined plane cam surface' 44, the elevational sight setting will be substantially at the midpoint of the anticipated elevational adjustment range required.

Slight adjustments of the lens are made to vertically align the axis of the lens 42 with the axis of the archers eye by loosening screw 25 and rotating the sight mount 22 on horizontal mounting stud 28. Slight adjustments of the lens to horizontally align the lens axis with the archers eye axis are made by backing off one or the other of set screws 40 and turning in the opposite one until alignment is accomplished. Windage adjustments are made by backing off a set screw 73 and then turning the windage screw knob 34 left or right as required. The set screw 73 is threadedly engaged in the pivoted member 18 and, when tightened, locks the windage screw 32 in an adjusted position.

I claim:

1. I n a sighting device for an archery bow, a sight bar, sighting means, a carriage slidably mounted on said sight bar, a cam surface extending along said sight bar, a sighting means supporting member pivotally mounted on said carriage to pivot about an axis, a cam follower on said supporting member engaging said cam surface and causing pivoting of said supporting member and sighting means when said carriage is slidably moved along said sight bar, and said cam follower being adjustably mounted on said sight supporting member to vary the distance from the pivotal axis of said sight supporting member to the point of contact of sai-d cam follower with said cam surface whereby the rate of rotational movement of said sight supporting member and said sighting means may be varied relative to the sliding of said carriage along said sight bar.

2. A sighting device as set forth in claim 1 in which said sighting means includes an optical lens, the optical axis of which is moved angularly about a substantially fixed center of rotation as said carriage is moved along said sight bar.

3. A sighting device as set forth in claim 1 in which said cam follower is slidably mounted for adjustment on said sighting means supporting member and is moved slidably thereon by screw' threaded means.

4. A sighting device as set forth in claim 1 in which guide means extending along both sides of said sight bar are engaged by cooperating means on said both sides of said carriage to closely guide said carriage along said sight bar and in which said cam surface is formed on said sight bar and extends therealong between said guide means. g

5. A sighting device as set forth in claim '1 in which said sighting means is mounted for manual rotational adjustment on said sight supporting member on vertical and horizontal axes.

6. A sighting 4device as set forth in claim 1 which further includes a set screw threadedly engaged in said carriage, a fiat surface having two ends extending along said sight bar so as to be engaged by said set screw which, when tightened against said surface, locks said carriage in a fixed position on said sight bar, and abutment means at the ends of said surface so as to be engaged by said set screw to prevent said carriage from sliding olf the ends of said sight bar when said set screw is loosened sufiiciently to permit free sliding movement of said carriage, and said abutments being of such height above said surface as to permit said carriage to slide olf of said sight bar when said set screw fis backed off considera'bly more than is necessary to permit the free sliding movement of said carriage.

7. 'In a sighting device as set forth in claim 1 which further includes means slidably mounting said sighting means transversely on said sight supporting member and screw threaded means threadedly engaged in said sight supporting member for moving said sighting means transversely of said sight bar. 

